Navidea Biopharmaceuticals is developing 18F-AZD4694 as a diagnostic imaging agent to be used with PET scans to directly visualize beta amyloid (A?) deposits in the brains of living patients. A? deposits in the brains of patients with dementia are diagnostic for Alzheimer's Disease. Al Alzheimer's Disease patients have abundant deposits of A? in their brains. Currently, it is very challenging or impossible to visualize or detect A? deposits in the brains of living patients. A? deposits are currently observed only at autopsy after a patient has died. Being able to visualize A? deposits would be extremely useful when evaluating patients with dementia because the absence of A? deposits in a patient's brain excludes a diagnosis of Alzheimer's Disease. This is important because, while Alzheimer's Disease is the most common cause of dementia in the elderly, many other types of dementia occur. Delivering the highest quality and most appropriate care to a patient with dementia requires that the cause or type of their dementia be correctly determined. The problem is that 15 percent - 23 percent of all patients given a diagnosis of Alzheimer's Disease in life tun out not to have A? deposits in their brains as determined by autopsy examinations. This means that these patients were misdiagnosed with Alzheimer's Disease and may not have received their best options for treatment. Being able to visualize A? deposits or the absence of A? in living brains would have avoided these misdiagnoses and dramatically improved the accuracy of dementia diagnoses. To commercialize 18F-AZD4694 and bring the benefits of this product to dementia patients, Navidea is proposing a study involving end of life patients with relatively short life expectancies. About a third of the enrolled participants in this study will have been diagnosed with Alzheimer's Disease. These patients will be imaged with 18F-AZD4694 while living. After their deaths, their brains will be collected and examined for the presence and amount of A? deposits. The goal of the proposed clinical study is to determine the correspondence between the amount of A? deposits predicted to be in the brains based on 18F-AZD4694 imaging and the actual amount of A? deposits detected at autopsy. Preclinical animal studies and indirect evidence from previously completed Phase I and Phase II clinical trial predict that the correspondence between A? detected by imaging and at autopsy will be very high. The successful completion of this trial is critical for securing allowance by the FDA to begi marketing 18F-AZD4694 for the purpose of excluding Alzheimer's Disease as a diagnosis for dementia patients who do not have Alzheimer's Disease.